Endoscopic measurements of intravascular pressure and flow in blood vessels of gastrointestinal tract

Abstract

Endoscopic measurements of flow and pressure in blood vessels of the gastrointestinal tract are very young techniques which have been described in the last three years. Laser doppler flowmetry provides measurement of blood flow in humans; the results are thought to reflect mucosal blood flow, at least in the stomach. Provided that the first encouraging results can be confirmed by further studies, the technique should open up new possibilities for endoscopic research. Endoscopic application of the doppler ultrasonic probe can be used to detect blood flow in the paravaterian region and in oesophageal varices. The clinical value of the detection of small arteries at the site of endoscopic papillotomy may be useful in the prevention of post-papillotomy bleeding. Since this complication rarely occurs, the clinical value of the doppler is likely to be limited in this field. Investigation of the flow pattern in oesophageal varices is a very interesting subject. The results, however, are not easy to understand. Further studies and the comparison of the pressure profile with the flow profile of the varix should provide better insight into portal hypertension pathophysiology. Due to its clinical importance, further interesting studies and results should ensue from this field. To date, most studies have involved measuring the pressure in oesophageal varices. Both the application of the pneumatic pressure gauge and the puncture technique are easy to perform. The simultaneous application of the two techniques (Staritz and Gertsch, 1985) revealed the advantages and disadvantages of the procedures. The invasive puncture provides exact and reproducible measurement of the IOVP in smaller varices (grade II) and the tracings are easy to read, whereas the pneumatic pressure gauge can only be attached to large varices (grade III and IV), and artefacts caused by respiration, patient's movements, oesophageal peristalsis and deviation of the pressure gauge from the variceal column affect the practicability of the procedure. The results simultaneously obtained by the two methods were only in accordance in some of the patients. The present form of the pressure gauge therefore needs improvement. Further investigations will elucidate whether the exact, reproducible, but invasive puncture technique can be replaced by less invasive pressure devices. Finally it should be pointed out that all endoscopic methods suffer from the common flaw that it is not yet clarified whether or not endoscopy affects flow and/or pressure in gastrointestinal vessels. Therefore, further studies should be carried out to establish the reliability of these methods.